Wednesday, September 25, 2013

IPCC says only way to lower temperatures is NEGATIVE CO2 emissions

According to New Scientist, the forthcoming IPCC report will say, "CO2-induced warming is projected to remain approximately constant for many centuries following a complete cessation of emission. A large fraction of climate change is thus irreversible on a human timescale, except if net anthropogenic CO2 emissions were strongly negative over a sustained period."

Global warming is irreversible without massive geoengineering of the atmosphere's chemistry. This stark warning comes from the draft summary of the latest climate assessment by the Intergovernmental Panel on Climate Change.

Delegates from national governments are discussing the draft this week, prior to its release on Friday morning.

According to one of its lead authors, and the latest draft seen by New Scientist, the report will say: "CO2-induced warming is projected to remain approximately constant for many centuries following a complete cessation of emission. A large fraction of climate change is thus irreversible on a human timescale, except if net anthropogenic CO2 emissions were strongly negative over a sustained period."

Much of this week's report, the fifth assessment of the IPCC working group on the physical science of climate change, will reaffirm the findings of the previous four assessments, published regularly since 1990.

It will point out that to limit global warming to 2 °C will require cumulative CO2 emissions from all human sources since the start of the industrial revolution to be kept below about a trillion tonnes of carbon. So far, we have emitted about half this. Current emissions are around 10.5 billion tonnes of carbon annually, and rising.